Short message service, which was first introduced by European wireless network operators in 1991, enables mobile subscribers to easily send and receive text messages via a wireless handset. As the convergence of wireless communication networks and Internet data networks has increased, the sending and receiving of SMS messages via computer terminals has also become commonplace. Although specifications and industry standards related to SMS are constantly evolving and being modified, SMS messages have traditionally been used to convey readable text information, where the text may include any combination of alphanumeric characters. After the initial text messaging application, service providers began focusing on using SMS as a means of eliminating alphanumeric pagers by permitting two-way general purpose messaging and notification services. One service that has been provided using SMS is voice mail notification service. As technology and networks continued to mature, a variety of services were introduced, including electronic mail (email) and fax integration, paging integration, interactive banking, and information services such as stock quotes, news highlights, etc.
SMS delivery service provides a mechanism for transmitting “short” messages to and from SMS-capable terminals (e.g., wireless handsets, personal computers, etc.) via the signaling component of the wireless communication network. With particular regard to the sending and receiving of SMS messages by a wireless handset, a wireless network provides the transport facilities necessary to communicate short messages between a short message service center (SMSC) and a wireless handset. A short message service center functions as a store and forward platform for short messages. In contrast to earlier text message transmission services, such as alphanumeric paging, SMS technology is designed to provide guaranteed delivery of an SMS message to a destination. That is, if a temporary network failure prohibits the immediate delivery of an SMS message, then the short message is stored in the network (i.e., at the SMSC) until the destination becomes available. Another of the key and distinguishing characteristics of SMS service with respect to previously available message communication services is that an active mobile handset is able to receive or transmit a short message at any time, regardless of whether or not a voice or data call is in progress.
SMS can be characterized as an out-of-band packet delivery technique with low per-message bandwidth requirements. Hence, SMS services are appealing to network owners and operators. FIG. 1 is a network diagram illustrating an SMS implementation in a global system for mobile communication (GSM) wireless network. It will be appreciated that a functionally similar SMS architecture could also be employed in non-GSM wireless networks. In any event, FIG. 1 includes a wireless communication network, generally indicated by reference numeral 100. Wireless network 100 includes a sending mobile terminal 110 that formulates and sends SMS messages and a base station system 112 that manages the network-to-air interface and reliably transmits the SMS message into the core wireless network. In this particular example, the receiving end of the network includes a base station system 126 and a receiving mobile terminal 128. Wireless network 100 also includes a pair of mobile switching centers (MSCs) 114 and 124, a pair of signal transfer points (STPs) 116 and 122, a short message service center 118 and a home location register (HLR) 120. SMSC 118 is responsible for relaying, storing, and forwarding short messages between sending and receiving SMS terminals. HLR 120 is a database platform used for permanent storage and management of mobile subscriber profiles and locations. HLR databases permanently store information about subscribers that belong to the same network as the HLR. A database element known as a visitor location register (VLR) is used to temporarily store information about subscribers who are currently “roaming” in the area serviced by the VLR. The VLR may belong to the subscriber's home network or to a non-home network. VLR databases are typically integrated within MSC network elements. Thus, a stand-alone VLR node is not shown in FIG. 1. The HLR and VLR store information needed to correctly route voice calls or data communications to a mobile subscriber. This information may include an international mobile station identification (IMSI), a mobile identification number (MIN), a mobile directory number (MDN), a mobile station ISDN number (MSISDN), and the identifications of the VLR and MSC with which the subscriber is currently associated.
With particular regard to short message service operations, HLR 120 provides SMSC 118 with network routing information for the receiving mobile subscriber or mobile terminal 128. In certain cases, HLR 120 may inform SMSC 118, which has previously initiated unsuccessful short message delivery attempts to a specific mobile station, that the mobile station is now recognized by the mobile network to be accessible.
MSC 114 is sometimes referred to as an SMS interworking MSC (SMS-IWMSC) because it is capable of receiving a short message from a wireless network and submitting it to the appropriate SMSC. In practice, SMS-IWMSC nodes are typically integrated with an MSC in the network, but may also be integrated with the SMSC. MSC 124 is sometimes referred to as an SMS gateway MSC (SMS-GMSC) because it is capable of receiving a short message from an SMSC, interrogating a home location register (HLR) for routing information, and subsequently delivering the short message to the “visited” MSC of the recipient mobile station.
FIG. 2 illustrates a communication network 150, which is a variation of the wireless network 100 described above with respect to FIG. 1. Network 150 includes a sending email client 152 and an email server 154, rather than sending mobile station 110 and base station 112. Email server 154 formulates SMS messages from email messages and forwards the SMS messages to SMSC 118. As such, an email message may be generated by a wireline computer terminal residing within a data network (e.g., the Internet) and sent to a mobile terminal within a wireless network as an SMS message.
The signaling infrastructure of wireless network 100 may be based on signaling system no. 7 (SS7), a telecommunications industry standard signaling protocol. SMS service uses the SS7 mobile application part (MAP), which defines the methods and mechanisms of signaling communication in mobile or wireless networks. The MAP protocol utilizes the transaction capabilities application part (TCAP) component of the SS7 protocol. Both North American and international standards bodies have defined a MAP layer using the services of the SS7 TCAP component. The North American standard is published by the Telecommunication Industry Association and is referred to as IS-41 MAP. The international standard is defined by the European Telecommunication Standards Institute and is referred to as GSM MAP.
FIG. 3 is an information flow diagram illustrating the delivery of a short message to a mobile subscriber or terminal in GSM wireless network. This diagram assumes the IWMSC and the GMSC node are both integrated into the SMSC node. Referring to FIG. 3, in step 1, a short message, such as a text message, is formulated by a sending mobile terminal and is transmitted via a signaling network to an MSC node. In response to receiving the short message, the MSC formulates a MAP-SEND-INFO-FOR-MO-SMS query message and transmits the message to the VLR node with which the mobile is currently registered (step 2). The VLR responds to the query and, if the receiving mobile subscriber (MS) is registered, provides the MSISDN corresponding to the IMSI to the MSC. Upon receiving the MS information, the MSC transmits the short message in a MAP-MO-FORWARD-SHORT-MESSAGE message to the SMSC (step 3). The SMSC sends a MAP-SEND-ROUTING-INFO message to the HLR of the SMS recipient using the recipient's MSISDN (step 4). The HLR responds with the IMSI of the recipient and the MSC with which it is currently registered. If the information indicates that the recipient is available (i.e. currently registered with an MSC and turned on with sufficient memory), the SMSC then transmits the short message to the MSC in a MAP-MT-FORWARD-SHORT-MESSAGE (step 5), and transmits a delivery report to the sending MSC (step 6). It will be appreciated that an SMSC attempts to deliver a short message to a receiving MS whenever the MS is registered and available (i.e. turned on with sufficient memory), even when the MS is engaged in a voice or data call. Such service is referred to as point-to-point delivery service and is accomplished via the use of the Short Message Delivery-Point-to-Point (SMD-PP) and ForwardShortMessage mechanisms in IS-41 and GSM, respectively.
In step 7, the MSC queries the VLR with which the recipient is currently registered with a MAP-SEND-INFO-FOR-MT-SMS message. The VLR returns location information associated with the receiving mobile subscriber (e.g., the MSISDN number associated with the receiving mobile subscriber). Using the information obtained from the VLR database, paging and authentication operations are initiated between the MS and the base station. Once the receiving MS has been authenticated and located, the MSC transmits the short message to the mobile (step 8). In step 9, information associated with the disposition or status of the SMS delivery attempt is returned to the SMSC.
It will be appreciated that such delivery status information may be used by the SMSC to ensure or guarantee the delivery of a particular message. That is, when a short message delivery attempt by the SMSC fails due to a temporary network failure, the SMSC may request that it be notified by the HLR when the indicated mobile subscriber becomes accessible. Such “message waiting” functionality is achieved using the SMS notification indicator in IS-41 and set message waiting data in GSM.
From the discussion of SMS operation fundamentals presented above, it will be appreciated that the SMS components of a wireless communication network will diligently attempt to deliver every SMS message received by the network. While such guaranteed delivery service is an attractive feature for legitimate mobile subscribers, the guaranteed delivery service may also cause a mobile subscriber's handset or terminal to be flooded messages in a manner that significantly inconveniences the subscriber or potentially even temporarily disables the subscriber's communication terminal. Furthermore, from a network operations perspective, SMS flooding incidents could have a significantly negative impact on overall network performance. Such SMS message flooding could be executed with malicious intent, or could simply be the unintentional result of a commercial advertising campaign. Accordingly, there exists a long-felt need for novel methods and systems for preventing an SMSC and/or a mobile subscriber from experiencing a mass delivery or flooding of SMS messages.